Cat seems to have an abscessed tooth, Is there anything I can do to help her until we can see her vet?

Hello! It's been a while since I posted to reddit but I'm anxious and wondering if any of you can point me in any kind of direction at all lol.

Today I noticed my cat Lila had what looked to be something white/light colored around her gums. When I looked closer, I realized it seemed to BE her gums. On her lower right side, around her canine, her gums are quite pale/yellowed and look...wrong? Swollen, for sure. Like pre-chewed gum, in a way, it's really jarring.

As today is Sunday, the vet I go to was not open and I could only leave a message. I plan on calling in again tomorrow to set up an appointment as soon as possible. She was recently at the vet for a UTI as well, and we learned she's in early stages of Kidney Disease and we still need to change out her food. Poor girl has been through the ringer lately.

Unfortunately, I can't take her in tomorrow as I have a doctor's appointment I can't put off or miss. I was recently diagnosed with diabetes and this is an intake appointment with a new doctor related to that.

I'm really worried about potential infection spread, as it already looks (and smells) pretty bad. Is there anything at all I can do in the meantime to make her more comfortable, to mitigate the harm (food I should avoid???) or things I should keep an eye out for that may be an urgent sign? I would show a picture but there's no way for me to hold her mouth open and snap a picture on my own.

As for symptoms and behavior...she had an appetite all day, but I hadn't realized until I saw her gums that she's been a little more sluggish the past day or two - it coincided with a heat wave here so I chalked it up to being warm and turned on the AC. She's been sluggish but eating and drinking water, and otherwise threw up once, but I have reason to believe it was genuinely just tummy upset from something she ate (she threw up a piece of sausage she wasn't supposed to sneak).

For reference; Lila is a spayed female, about 16 (our best estimate at least), weighed 6.8lbs at her last appointment (which was only a couple weeks ago at most), and seems to be a shorthair/Siamese mix of some kind.

I'm sorry this post is all over the place, this is one in a list of multiple medical things that have happened lately and I'm pretty frazzled and at a loss. I'm trying to keep up and keep her safe and taken care of, but it feels like so much keeps happening and I'm really scared I'm going to fail her by not reacting fast enough. Any advice or help is much appreciated, thank you.